Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation (EA) is one such method. EA toners may be used in forming print and/or electrophotographic images. EA techniques may involve the formation of an emulsion latex of the resin particles by heating the resin using a batch or semi-continuous emulsion polymerization, as disclosed in, for example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,902,710; 5,910,387; 5,916,725; 5,919,595; 5,925,488, 5,977,210, 5,994,020, and U.S. Patent Application Publication No. 2008/0107989, the disclosures of each of which are hereby incorporated by reference in their entirety.
Combinations of amorphous and crystalline polyesters may be used to form toners having relatively low-melting point characteristics (sometimes referred to as low-melt, ultra low melt, or ULM), which allows for more energy-efficient and faster printing.
EA toner processes include coagulating a combination of emulsions, i.e., emulsions including a latex, wax, pigment, and the like, with a flocculent such as polyaluminum chloride and/or aluminum sulfate, to generate a slurry of primary aggregates which then undergo a controlled aggregation process. A stable triboelectric charge is very important for toner performance. Residual surfactants and/or ions on the toner surface play very important roles in toner charging, charging maintenance, and relative humidity (RH) sensitivity. Currently, a washing process using water is used to remove surfactants/ions on the particle surface. However, this washing process is not very effective, as it requires a large amount of washing water, multiple washing steps and a long cycle time. Additionally, this conventional washing process can only wash off surfactants/ions from the particle surface, but cannot wash out surfactants/ions just beneath the outer particle surface, which may also be critical to triboelectric performance of the toner particles.
Improved methods for producing toners having stable charging characteristics remain desirable.